During the opening sequence, the get-away car hits a deer, smashing the windshield and covering it with blood. In the following shots showing the car careening out of control, the windshield is intact with no damage.
When Travis, one of the officers, is killed by getting clotheslined through the barbed wired fence, the initial shots don't show any damage to his jacket. At 58:05, 58:25 and 58:40 it all shows his jacket as normal, with no tears, only with some blood on it. Then when you see Hannah's dad (the sheriff) looking at Travis (dead at this point) around the 103:45 mark, it looks like the barbed wired fence caught the jacket and ripped holes in it or it even looks like a buck shot to the chest during the initial gun fight at the cabin.
At Bobby's hunting cabin, when Addison listens to Liza's voicemail he has one stream of blood running down his forehead. When he turns around to write down an address, he has an extra stream of blood running down his cheek. And when he turns back around the stream is gone.
While the movie is supposedly set in Michigan around Detroit, an early scene show's a Dunn's Delicatessen and the Dominion Square Tavern, both recognizable landmarks on Metcalfe Street in Downtown Montreal.
With the understanding that movie is set near the near the Detroit area. The early in the film the sheriffs established a search area from the lake shore (Lake Huron) to I-75. In the next scene Jay is driving down the road and sees a road block, which happens to be US-131. US-131 is very distant and runs up the west side of the state where I-75 runs up the east side. The I-75 and US-131 do not converge or cross.
Jay's parents are said to live near the border of Canada when he is talking to Liza, however, at the bar when Liza is going through Jay's mail in the truck the address is listed as "Bear Lake, MI 016522" which is nowhere near the Canadian border,it's on the other side of Michigan by Lake Michigan, also, that zip code is one too many digits.